Molded impeller



Nov. 16, 1948. r K. PERKINS IOLDED IIPELLER rma ont. 16. 1944 ATTORNEY Patented Nov. 16, 19484 ori-ica MOLDED IMPELLER Kenneth Perkins, Scotch Plains, N. J.. assignor to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey Application October 16, 1944, Serial No. 558,823

2 Claims. (Cl. 17o-159) blades of the impeller having hollow air foil sec-4 tions.

Another obiect of this invention is toproduce a molded air impeller, having suitable aerodynamic characteristics, from two parts which may be molded from plastic material and when unitedV form an impeller having hollow blades, the impeller being light in weight. yet strong and rigid enough to withstand vibration and in which the two parts are bonded together along the leading and trailing edges of the blades so that the assembled impeller has the appearance of being molded in a single piece.

Another object of this invention is to produce an impeller having hollow molded blades each of which is formed with strengthening ribs extending longitudinally and transversely of the blade, the ribs being formed so that they-conform to the nished edges of the blade and that in the direction of their height they are arranged parallel to each other and to the axis about which the impeller is adapted to rotate.

Another and further object of this invention is to form the impeller from 'transparent plastic material and to coat the inner surface of the hollow blade with a metallic lacquer to give the appearance of depth and to produce a generally pleasing effect on an observer.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from lwhich the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

In the drawings:

Figure 1 is a front view of an air impeller having four blades, one oi' which and a portion of the hub is shown in section.

Figure 2 is a vertical section taken along the line 2-2 of Figure 1.

Figure 3 is a vertical section taken along the 4line 3-3 of Figure 1.

and l radiating from a hub indicated generally as 5. The impeller is made in two parts I3 and u (Figs. 2 and 3); the part ls forming the backl of the impeller and the part I5 the front. The parts I3 and I4 are each molded in a single piece. Either thermoplastic or thermosetting materials may be used, particular examples of Iwhich are the phenol formaldehyde resins,- methylmethacrylate resins an-d cellulose acetate. If desired, the two parts of the impeller may be molded of .a transparent plastic material and the inner surfaces coated with a metallic lacquer for the purpose of giving an appearance of depth to theV surface of the blade.

The part I3 has each oi its blade portions formed with longitudinally arranged ribs 6, having a curvature corresponding to the curvature of the leading and trailing edges of the blade, and

transverse ribs 6 each having the axis of the impeller as the center of curvature. The ribs 6 and 6' are arranged on the part I8 so that depthwise they extend in a direction parallel to the axis of the impeller, thereby preventing negative angles and providing the necessary draft to permit the molds to be withdrawn after the molding operation.

Molded in the center of the hub 6 is an inner cylindrical portion Il which surrounds a metal sleeve Il adapted to be mounted on the shaft of the fan motor. The inner cylindrical portion II is connected to an outer cylindrical portion I2 by the radially extending ribs I0 and the bottom wall I0 (Fig. 2). From the above it will be understood that the hub 5 is in effect a cylindrical cup-shaped member having a central portion connected with the rim portion by a base and a series of strengthening ribs.

The front part I4 of the impeller is likewise molded in one piece from either thermoplastic or thermosetting material and. in effect, is a cover for the back or rear part I3. Each of the lblades of the part I 3 is formed with a groove 1 encircling the hollow portion of the molded blade and the front part I4 is formed with a land 8 conforming 0 fin size and shape to the groove 'l and is complemental thereto. The front part or cover I4 conforms exactly in size and shape to the back part I3 so that, when the parts I3 and I4 are assembled, the bracing ribs 6 and 6 will engage the inner surface'of the front part I4, thereby avoidlng vibration or flexing of the part I4 under` wind loading. The parts I3 and I4 may be secured together by any suitable means, but I prefer to use a thermoplastic adhesive or the like so that theY assembled impeller has the appearance of to have impressed therein the name of the manufacturer.

A molded impeller made inA accordance with the -foregoing description has a low inertia, yet is strong and durable and will not distort when subjected to a wind load. Due to the fact that the cross-sectional areas of the molded material are thin, the molding operation does not produce dimples, as is the case when thick cross-sections are molded. and the strengthening ribs 6 and S prevent distortion thereby obtaining molded blades which properly track; and as the blades have air foil sections, a quiet impeller for fans is obtained from thermoplastic or thermosetting material.-r

Having thus set forth the nature of the invention,what I claim herein is:

l. An air impeller formed in two parts from plastic material, one of said parts being formed with a hub from which a plurality of blades radiate, said blades having a cup-shaped portion formed with a series of longitudinally and laterally arranged ribs, the other part having a central portion which covers said hub and a pluralityof blades complementa] to the blades on said first mentioned part, and means for securing said parts together to form an air impeller having hollow blades with air foil sections.

2. An air impeller, designed to be produced by molding; comprising a hollow inner cylindrical hub portion the wall of which is axially aligned; an outer "open-front cylindrical-hub portion formed coaxial with said inner hub portion; a bottom-wall hub portion connecting said inner and outer hub portions; a plurality of radial rib portions extending intermediate said inner and outer hub portions; a plurality of impeller-blade back-portions formed integral with and extending laterally from said outer hub portion, each 4 impeller-blade back-portion being formed with a hollow therein and having a groove encircling said hollow; a plurality of ribs formed integral with said back portion and positioned in said hollow, said ribs extendng laterally from said hub peller-blade back-portions and the inner surface of said blade cover-portions engaging said plurality of ribs, a land portion formed integral with each of said ,blade cover-portions, said land portion conforming in size and shape and being complemental to the groove in said back bladeportion; and means for securing said parts together.

i KENNETH PERKINS.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS Name Date Clifton June 19, 1928 Baumann July 2, 1935 Baker Oct. 1, 1940 Dornier Oct. 14, 1941 Schwartz Oct. 21, 1941 Brinkmann July 14, 1942 Brotz Apr. 11, 1944 FOREIGN AfrENTs Country Date 'Great Britain Apr. 17, 1939 Great Britain May 2, 1939 Number Number 

